In a manufacturing process of semiconductor circuit elements, dry etching is conventionally performed to form via holes in an interlayer insulating film formed on a substrate using a photoresist pattern as a mask, or to pattern a film of wiring material such as aluminum. As a conventional postprocessing of dry etching, the photoresist pattern is removed by ashing, then photoresist residues and polymer residues remained partially on the treated surface are removed by an exclusive removing liquid (residue-removing liquid composition). Here, photoresist residues refer to incomplete ashed products such as photoresists and antireflection coatings remained on the substrate surface after ashing that is performed after dry etching, and polymer residues refer to by-products during dry etching, which include fluorocarbon deposits derived from an etching gas, remained as a by-product on the wall surface of the etched material, side-wall polymers (also called as side-wall protection film and rabbit ear) derived from a compound of wiring material and etching gas, and organic metal polymers and metal oxides remained on the side wall and bottom of via holes.
As conventional liquids for removing a photoresists residue and a polymer residue, in cases where wiring material is aluminum or aluminum alloys, a composition consisting of “fluorine compound+quaternary ammonium compound+water” or “fluorine compound+quaternary ammonium compound+organic solvent+water” and a composition consisting of “hydroxylamine+alkanolamine (+solvent)” are proposed (for example, refer to Patent Literatures 1 and 2). These compositions have low corrosiveness to aluminum or aluminum compounds, and they can be applied to either after the formation of metal wiring or after the formation of via holes or contact holes; however, they require long time of treatment such as 20-30 min in order to remove residues completely. Accordingly, these compositions cannot be applied to single wafer cleaning apparatuses which have been progressively introduced in residue-removal processes and which require low-temperature short-time processing (as a guide, processing temperature is around 25-40° C., and processing time is around 1-3 min).
Furthermore, in recent years, when using a single wafer cleaning apparatus, attempts have been made to remove polymer residues remained after dry etching of aluminum or aluminum alloys upon wiring formation, and photoresist residues and polymer residues remained after dry etching of interlayer insulating films upon formation of via holes, using a single liquid composition for removing a photoresists residue and a polymer residue. For example, a composition consisting of “quaternary ammonium compound+hydrogen peroxide+water” or “carboxylate+hydrogen peroxide+water” has been reported (for example, refer to Patent Literature 3 and Patent Literature 4). When used individually, these compositions are reported to be capable of removing photoresist residues simultaneously with polymer residues mainly comprised of titanium oxides remained at the bottom and side walls of via holes, when the bottom of the via holes is TiN. However, any of these compositions contain hydrogen peroxide; when the content of hydrogen peroxide is high, aluminum or aluminum alloy is corroded; when the content of hydrogen peroxide is low, then polymer residues mainly comprised of titanium oxides cannot be removed and applicable processing temperature and processing time are restricted. In addition, oxidizing agents tend to decompose easily and the temporal stability of the compositions themselves becomes a problem.
As composition without hydrogen peroxide, a composition consisting of “acid+inorganic salt” has been reported. As an example of compositions in which fluorine compound is combined with acids, a composition consisting of “fluorine compound+sulfuric acid+hydrogen peroxide or ozone+water” has been reported to be capable of removing photoresist residues and polymer residues at low temperature under short processing time, which also has a weak corrosive action on aluminum alloys (for example, refer to Patent Literature 5). However, these compositions do not show sufficiently weak corrosive actions on aluminum or aluminum alloys in actual application to single wafer cleaning apparatuses, and the concentration of the fluorine compound is low, such as 100 ppm at maximum; accordingly, the removal of photoresist residues remained on the surface of interlayer insulating films upon formation of via holes and polymer residues containing titanium oxides remained at the bottom of via holes and their surroundings is not sufficient. Moreover, hydrogen peroxide or ozone is easy to be decomposed, so that the temporal stability of the composition itself becomes a problem.
The present inventor and colleagues have reported that a composition consisting of “inorganic fluorine compound+inorganic acid” can also remove photoresist residues and polymer residues at low temperature with short processing time, and that the composition has a weak corrosive action on aluminum alloys (for example, refer to Patent Literature 6). Since this composition does not contain hydrogen peroxide or ozone, its corrosive action on aluminum alloys is weaker than that of the composition containing “fluorine compound+sulfuric acid+hydrogen peroxide or ozone+water”, so that temporal stability of the former composition is superior; however, because its content of inorganic fluorine compound is 0.01-0.05 mass %, it cannot sufficiently remove photoresist residues remained on the surface of interlayer insulating films upon formation of via holes and polymer residues containing titanium oxides remained at the bottom of via holes and their surroundings. Furthermore, the present inventor and a colleague reported a composition consisting of “fluorine compound (excluding hydrofluoric acid) and sulfonic acid” (for example, refer to Patent Literature 7). This composition has high content of a fluorine compound, and by using organic sulfonic acid, its capability of removing photoresist residues on the surface of via-hole patterns upon formation of the patterns has been successfully improved, compared to that of the above-mentioned composition consisting of “inorganic fluorine compound+inorganic acid,” but its capability of removing titanium oxide at the bottom of via holes and their surroundings is still insufficient. To remove polymer residues containing titanium oxides using such a composition, the contents of fluorine compound and sulfonic acid should be increased; in this case however, its corrosive action on interlayer insulating films and aluminum alloys would be significantly enhanced.
Meanwhile, as a composition to remove photoresist residues and polymer residues formed in dry etching upon formation of substrates without wiring, compositions such as “sulfuric acid 5-7+hydrofluoric acid 1/400-1/1000 (volume ratio)”, “sulfuric acid 5-7+hydrogen peroxide 1+hydrofluoric acid 1/400-1/1000 (volume ratio)” have been reported; however, since the contents of water and hydrofluoric acid are low, removal of photoresist residues under low-temperature processing is not sufficient, and under high-temperature processing, various metal-wiring materials are corroded (for example, refer to Patent Literature 8).
Other than the above, a composition consisting of “ammonium fluoride+organic acid+water” has been reported (for example, refer to Patent Literature 9); however, there is a concern regarding deterioration of workability due to odor of acetic acid used as the organic acid. A composition consisting of “fluorine compound+acids having a reducing character” is also able to remove photoresist residues and polymer residues at low temperature and in a short time and has a weak corrosive action on copper, copper alloys and low-dielectric-constant films (for example, refer to Patent Literature 10); however, it does not have sufficient capability of corrosion prevention of aluminum and aluminum alloys.
As an example of compositions wherein fluorine compound is combined with acids and organic solvent, a composition consisting of “fluorine compound+ascorbic acid+polar organic solvent” (for example, refer to Patent Literature 11) has been reported; however, because ascorbic acid itself decomposes with time in an aqueous solution, the composition is not practically applicable. While a composition consisting of “fluorine compound+orthoboric acid or orthophosphoric acid+aqueous organic solvent” (for example, refer to Patent Literature 12) aims to remove photoresist residues and polymer residues upon formation of via holes, actually its ability of removing resist residues and polymer residues containing titanium oxides is too low. In addition, this composition exhibits a strong corrosive action on metals such as aluminum, when its contents of water and fluorine compound are increased in order to increase its ability to remove polymer residues. Furthermore, a liquid composition for removing a photoresists residue and a polymer residue consisting of “fluorine compound+sulfonic acid buffer+aqueous organic solvent” (for example, refer to Patent Literature 13) has a weak corrosive action on copper, but there is no description regarding its capability of corrosion prevention of aluminum, etc.
While this is not a liquid composition for removing a photoresists residue and a polymer residue after dry etching, there is a report on a surface-treatment agent for the surface of a polysilicon film formed on an insulating substrate made of glass, etc. using laser annealing method, consisting of “0.01-0.5 mass % of hydrofluoric acid or 0.5-5 mass % of ammonium fluoride+50.0-80.0 mass % of nitric acid” (for example, refer to Patent Literature 14); however, with 0.01-0.5 mass % of the hydrofluoric acid, the removal of photoresist residues is not sufficient. Furthermore, in examples of this literature, there is only a description of composition with a nitric acid content of 50.0-70.0 mass %; however, since the water content is too large with this range of composition, corrosion of metals such as aluminum, etc. becomes obvious.
As described above, to date there is no example in which a single liquid composition for removing a photoresists residue and a polymer residue has both a good removing property to remove photoresist residues and polymer residues (in particular, polymer residues containing titanium oxides) by a low-temperature and short-time processing using a single wafer cleaning apparatus, and a capability of corrosion prevention of metal wiring. Therefore, development of a liquid composition for removing a photoresists residue and a polymer residue having these characteristics has been desired.    Patent Literature 1: JP A No. 7-201794    Patent Literature 2: U.S. Pat. No. 5,334,332    Patent Literature 3: JP A No. 2002-202617    Patent Literature 4: JP A No. 2005-183525    Patent Literature 5: JP A No. 11-243085    Patent Literature 6: JP A No. 2005-173046    Patent Literature 7: JP A No. 2006-66533    Patent Literature 8: JP A No. 11-135473    Patent Literature 9: JP A No. 6-349785    Patent Literature 10: JP A No. 2003-280219    Patent Literature 11: JP A No. 2001-5200    Patent Literature 12: JP A No. 11-67703    Patent Literature 13: JP A No. 2003-241400    Patent Literature 14: JP A No. 2002-43274